Fluid amplifier with improved interaction region

ABSTRACT

A fluid amplifier having a power nozzle for supplying fluid into an interaction chamber, and a pair of control nozzles adapted to control the flow of the fluid into a pair of output receivers. At least one of the sidewalls of the interaction chamber has a configuration that is effectively defined by a curve having a logarithmic configuration.

0 United States Patent l 13,568,701

[72] Inventor George Mon [56] References Cited W 8 M UNITED STATES PATENTS [21] P 803507 3,187,763 6/1965 Adams 137/815 [22] 1969 3 266 s 10 8/1966 Wade 137/81 s {45] Patented Mar. 9,1971 y [73] Assignee The United States of America as represented Primary Examiner-William Cline by the Secretary of the Army AttorneysHarry M. Saragovitz, Edward J. Kelly, Herbert Berl and J. D. Edgerton [54] IMPROVED ABSTRACT: A fluid amplifier having a power nozzle for sup- 8 Claim 1 D F plying fluid into an interaction chamber, and a pair of control rawmg nozzles adapted to control the flow of the fluid into a pair of [52} US. Cl 137/81.5 output receivers. At least one of the sidewalls of the interac- [51] Int. Cl. F15c 1/06 tion chamber has a configuration that is effectively defined by [50] Field of Search 137/815 a curve having a logarithmic configuration.

300 l E Q PATENTE-U "AR 9 |97| MZ/I mm INVENTOR.

GEORGE MON BWM- W)! amfiiw ATTORNEYS FLUID AMPMFHER WETH IMPROVED HNTEZRACTKON REGION BACKGROUND-OF THE INVENTION This invention relates to a fluid amplifier, and, more particularly, to a bistable fluid amplifier having an interaction chamber whose sidewalls are defined by a curve having a logarithmic configuration.

Fluid amplifiers have been proposed in which a power jet nozzle supplies an interaction chamber, with a pair of control nozzles controlling the flow of fluid through the amplifier to one of a pair of output receivers. in .these proposals-the sidewalls of the interaction chamber are usually defined by a straight line, or by a convex curve having a constant radius. However, in these type arrangements, the fluid jet will separate from the surface of the receiver in which it is flowing at a pointsomewhere downstream from the interaction chamber, the location of this point being dependent on the Reynolds number of the fluid jet. When this occurs the performance of the amplifier is limited and, under certain conditions, the amplifier will cease to operate.

SUMMARY OF THE INVENTION lt is therefore an object of the present invention to provide a bistable fluid amplifier which has a relatively broad range of operation.

it is a further object of the invention to provide a bistable fluid amplifier which has relatively low power, a high pressure recovery, and a high fan-out.

Briefly summarized, the fluid amplifier of the present inven-- tion includes a power nozzle, an interaction chamber, and a pair of outlet channels, with at least one of the sidewalls of the interaction chamber havinga configuration that is effectively defined by a curve of a logarithmic configuration.

BRIEF DESCRIIPTION OF THE DRAWING BRlEF DESCRlPTlON OF THE PREFERRED EMBODlIVlENTS The amplifier according to the present invention is shown in plan view for convenience of presentation, it being understood that it may be constructed in any known manner, such as by etching the various flow channels into a base plate, and covering same with a covering plate, as is well known in the art.

As shown, a power jet nozzle supplies fluid at a predetermined pressure through a throat 112 into an interaction chamber 14. From the latter chamber the fluid jet passes into one of two output receivers to and 18 which are divided by a splitter 20. A pair of control nozzles 22 and 24 are provided, through which a control fluid flow can be selectively supplied to the fluid jet in the interaction chamber 14 to deflect the fluid jet to one of the output receivers 16 or 13, respectively. A pair of bleeder channels 26 and 2b can also be provided between the interaction chamber and the output receivers, as shown. Since this basic arrangement is well known in the art, it will not be described in any further detail.

According to the present invention, the sidewalls 30 and 32 of the interaction chamber lid are each formed of a curved surface defined by a positive and negative logarithmic spiral. in particular, each of the upstream portions 3th: and 32a of the sidewalls 30 and 1'32, respectively, are of a convex shape and are formed by a curve in the form of a positive logarithmic spiral. Likewise, each of the downstream portions 30b and32b are of a concave shape, and are formed by a curve in the form of a negative logarithmic spiral.

By logarithmic spiral is meant a spiral curve defined about a centerpoint having a radius equal to Ke"0, in which 6 is the angular position of a point on the spiral and if and n are constants. Since the portions Zifla and 3320 are convex, they conform to the outside of a spiral curve and hence are described as conforming to a positive spiral curve. The portions 30b and 32b being convex are described as conforming to a negative spiral. Both the positive and negative spirals to which the walls 30 and 32 conform are of increasing radius proceeding downstream. The transition between the convex portion and the concave portion may occur at substantially the midpoint of each sidewall on a tangent common to both the concave and convex portions, and the outer sidewalls of the receiver lie on tangents to the convex portions. The upstream end of the splitter 20 is positioned within the chamber 14 between the concave portions 30b and 32b, as shown.

In operation, fluid from the power nozzle ill flows through the throat 12 into the interaction chamber 14 whereby it attaches itself to either sidewall 30 or 32 by means of the well known Coanda effect, and then passes out through one of the corresponding output receivers 16 or 18, respectively.-A control signal, in the form of a fluid flow from the control nozzle 22 or 24, can be applied to the main fluid jet in the interaction chamber 14 to switch the flow to the output receiver 16 or 18, respectively.

Asia result of the convex logarithmic configuration of the sidewiall portions 30a and 32a, the static pressure along these porticins is lower than the static pressure would be if the surface were straight, or defined by a constant radius curve. This low static pressure causes the fluid jet to lock to the surface more readily than it would otherwise, thus permitting a broader range of operation and making it possible to use a laminar flow instead of a turbulent flow at the power jet.

As a result of the concave logarithmic configuration of the sidewall portions 39b and 3212, the spreading rate can be slowed down, and the rate of decay of the maximum velocity of the fluid jet is decreased thus permitting the splitter 20 to be placed closer to the power nozzle to increase the pressure recovery.

lt therefore follows that the fluid amplifier of the present invention enjoys an improved performance and an extended range of operation when compared to the prior art bistable fluid amplifiers discussed above.

Of course, variations of the specific construction and arrangement of the fluid amplifier disclosed above can be made by those skilled in the art' without departing from the invention as defined in the appended claims.

I claim:

l. A fluid amplifier having a power nozzle, an interaction chamber, and a pair of output receiver s, wherein the improvement comprises at least a portion of one of the sidewalls of the interaction chamber having a configuration that is effectively defined by a curve of a logarithmic spiral configuration of increasing radius proceeding downstream.

2. A fluid amplifier as recited in claim 1 wherein said interaction chamber is substantially symmetrical about the axis of the amplifier, whereby at least a portion of both of said sidewalls have said configuration.

3. A fluid amplifier as recited in claim 1 wherein said portion is convex.

4. A fluid amplifier as recited in claim 3 wherein said one of said sidewalls has concave portion downstream from said convex portion.

5. A fluid amplifier as recited in claim 3 wherein said convex portion connects to said concave portion on a tangent commonto both said convex and concave portions.

6. A fluid amplifier as recited in claim 3 wherein said concave portion conforms to a negative logarithmic spiral of increasing radius proceeding downstream.

7. A fluid amplifier as recited in claim 3 wherein said sidewalls have upstream convex portions and downstream concave portions and wherein said receivers are divided by a splitter extending between said concave portions.

concave portions conform to negative logarithmic spirals of increasing radius proceeding downstream. 

1. A fluid amplifier having a power nozzle, an interaction chamber, and a pair of output receivers, wherein the improvement comprises at least a portion of one of the sidewalls of the interaction chamber having a configuration that is effectively defined by a curve of a logarithmic spiral configuration of increasing radius proceeding downstream.
 2. A fluid amplifier as recited in claim 1 wherein said interaction chamber is substantially symmetrical about the axis of the amplifier, whereby at least a portion of both of said sidewalls have said configuration.
 3. A fluid amplifier as recited in claim 1 wherein said portion is convex.
 4. A fluid amplifier as recited in claim 3 wherein said one of said sidewalls has concave portion downstream from said convex portion.
 5. A fluid amplifier as recited in claim 3 wherein said convex portion connects to said concave portion on a tangent common to both said convex and concave portions.
 6. A fluid amplifier as recited in claim 3 wherein said concave portion conforms to a negative logarithmic spiral of increasing radius proceeding downstream.
 7. A fluid amplifier as recited in claim 3 wherein said sidewalls have upstream convex portions and downstream concave portions and wherein said receivers are divided by a splitter extending between said concave portions.
 8. A fluid amplifier as recited in claim 7 wherein each of said convex portions conform to positive logarithmic spirals of increasing radius proceeding downstream and each of said concave portions conform to negative logarithmic spirals of increasing radius proceeding downstream. 